[PATCH GCC]Correct cand_chain and stmt_cand_map for copy/cast

[PATCH GCC]Correct cand_chain and stmt_cand_map for copy/cast

[bin.cheng]

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Hi,
I noticed that cand_chain (first_interp/next_interp) is not maintained correctly
in slsr_process_copy/slsr_process_cast (now slsr_process_copycast).  This one
fixes the issue, as well as records the "first" cand in stmt_cand_map.

Hi Bill, is this correct or I misunderstood the code? Bootstrap and test on x86_64.

Thanks,
bin

2019-05-15  Bin Cheng  <bin.cheng@linux.alibaba.com>

        * gimple-ssa-strength-reduction.c (slsr_process_copycast): Record
        information about next_interp and the first cand.

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diff --git a/gcc/gimple-ssa-strength-reduction.c b/gcc/gimple-ssa-strength-reduction.c
index c30793a91bd..0483058d78d 100644
--- a/gcc/gimple-ssa-strength-reduction.c
+++ b/gcc/gimple-ssa-strength-reduction.c
@@ -1680,7 +1680,7 @@ slsr_process_copycast (gimple *gs, tree rhs1, bool speed)
 
   if (base_cand && base_cand->kind != CAND_PHI)
     {
-      slsr_cand_t first_cand = NULL;
+      slsr_cand_t last_cand = NULL;
 
       while (base_cand)
 	{
@@ -1693,17 +1693,19 @@ slsr_process_copycast (gimple *gs, tree rhs1, bool speed)
 	     In case of cast, the type is not propagated because it comes
 	     from the cast, and the base candidate's cast, which is no
 	     longer applicable.  */
-	  c = alloc_cand_and_find_basis (base_cand->kind, gs,
+	  c2 = alloc_cand_and_find_basis (base_cand->kind, gs,
 					 base_cand->base_expr,
 					 base_cand->index, base_cand->stride,
 					 ctype, base_cand->stride_type,
 					 savings);
-	  if (!first_cand)
-	    first_cand = c;
-
-	  if (first_cand != c)
-	    c->first_interp = first_cand->cand_num;
-
+	  if (!c)
+	    c = c2;
+	  else
+	    {
+	      c2->first_interp = c->cand_num;
+	      last_cand->next_interp = c2->cand_num;
+	    }
+	  last_cand = c2;
 	  base_cand = lookup_cand (base_cand->next_interp);
 	}
     }

Re: [PATCH GCC]Correct cand_chain and stmt_cand_map for copy/cast

[Richard Biener]

On Wed, May 15, 2019 at 7:54 AM bin.cheng <bin.cheng@linux.alibaba.com> wrote:
>
> Hi,
> I noticed that cand_chain (first_interp/next_interp) is not maintained correctly
> in slsr_process_copy/slsr_process_cast (now slsr_process_copycast).  This one
> fixes the issue, as well as records the "first" cand in stmt_cand_map.
>
> Hi Bill, is this correct or I misunderstood the code? Bootstrap and test on x86_64.

Looks good to me, still waiting for Bills feedback (now CCed).

Richard.

> Thanks,
> bin
>
> 2019-05-15  Bin Cheng  <bin.cheng@linux.alibaba.com>
>
>         * gimple-ssa-strength-reduction.c (slsr_process_copycast): Record
>         information about next_interp and the first cand.

Re: [PATCH GCC]Correct cand_chain and stmt_cand_map for copy/cast

[Bill Schmidt]

On 5/15/19 6:09 AM, Richard Biener wrote:
> On Wed, May 15, 2019 at 7:54 AM bin.cheng <bin.cheng@linux.alibaba.com> wrote:
>> Hi,
>> I noticed that cand_chain (first_interp/next_interp) is not maintained correctly
>> in slsr_process_copy/slsr_process_cast (now slsr_process_copycast).  This one
>> fixes the issue, as well as records the "first" cand in stmt_cand_map.
>>
>> Hi Bill, is this correct or I misunderstood the code? Bootstrap and test on x86_64.
> Looks good to me, still waiting for Bills feedback (now CCed).

Good catch, thanks for fixing!  Okay for trunk.

My mail server seems to have eaten the patch that introduces slsr_process_copycast.
This is okay for trunk also, with one grammatical nit.  Please change the comment
before alloc_cand_and_fine_basis to read:

"In case of a cast, the type is not propagated because it comes from the cast;
nor is the base candidate's cast, which is no longer applicable."

I'm very sorry for the delay due to vacation.

Thanks!
Bill

>
> Richard.
>
>> Thanks,
>> bin
>>
>> 2019-05-15  Bin Cheng  <bin.cheng@linux.alibaba.com>
>>
>>         * gimple-ssa-strength-reduction.c (slsr_process_copycast): Record
>>         information about next_interp and the first cand.